The tool can be worn seriously when Al/SiCp composite is machined due to the SiC particles with a higher hardness. Based on the new nano-cemented carbide characterized by his high hardness,toughness,flexural strength and higher wear resisting property,a WC-7Co nano cemented carbide tool was prepared, and the cutting experiment was carried out.The wear mechanism of nano cemented carbide tool and chip removal mechanism were studied. Results show that the wear mechanism of nano cemented carbide tool is an abrasion wear due to the micro-cutting of SiC particles and the micro-chipping and micro-breakage of cutting edge caused by interrupted impact of the SiC particles under the high frequency. The essence of cutting Al/SiCp is interrupted cutting,and the Al/SiCp chip removal is the breakout of chip.Experiment indicates that the flank wear value of nano cemented carbide tool is about 30%-50% less than that of common cemented carbide,which means nano cemented carbide is more suitable for machining Al/SiCp composite than common cemented carbides.